Ball valves of various designs are widely used in business and industry for controlling substances like water, brines, and petrochemical, air, gasses, and all types of fluids at various temperatures and pressures. These valves typically are made of various suitable materials, such as brass, iron, steel, stainless steel and other metals and also frequently made of plastic. Most are manually controlled by various handles connected to a protruding valve stem that can be rotated to move the directly connected ball, at a lowest end of the stem, from a fully open orientation to a fully closed orientation and back to a fully open orientation or at any various angle open orientation in-between. In some cases, instead of handle-operated or wrench-operated stems some ball valves may be operated by an electric, air or hydraulic powered actuator motor, which is mounted on the valve and directly connected to the valve stem in order to open, close, or modulate the ball valve.
In manually-operated ball valves, it is important to have a virtually leak proof stem seal design to prevent fluid leakage to the atmosphere. This is usually achieved by use of a conventional stem packing gland whose flexible packing material can be tightened or loosened in response to rotation of a threaded gland packing nut. In some cases a non-adjustable gland is used which employs a spring for consistent gland loading, the spring may be a wave spring or conventional coiled wire compression spring.
It is necessary to use sufficient force on the packing to squeeze it enough to achieve leak tightness between the inner diameter of the packing and the outer diameter of the rotating valve stem, as well as the non-rotating sealing of the outer diameter of the packing to the valve body stem housing or bonnet bore. As valve body and fluid temperatures change, the packing tends to expand or to contract in response thereto thereby encouraging stem leakage. In order to ensure a leak tight condition, the adjustable or non-adjustable packing is typically excessively tightened, which thereby results in increased friction against the valve stem and consequently the need for higher torque to rotate the stem in the packing, which in turn requires components to accommodate such higher torque requirements.
In the case of a manually rotating stem using a handle or an operating wrench such resulting high rotational torques requirement can be overcome by using the operator's hand, arm and/or or body to apply more torque. However, when a motor operator is used for such a ball valve, the motor must be oversized to achieve the high torque required to rotate the stem in the tightened packing conditions. Further, most ball valves use handles which exert a side thrust on the valve stem as rotation is accomplished against the opposing torque from friction of the stem packing and the valve seal washer. This side thrust causes friction between the valve stem and the bore in the valve body stem bonnet, which results in greater torque being required to move the ball, especially when the stem is longer than a mere inch or so out of the valve body.
Most ball valves have a washer-shaped ball seal on each side of the ball. To achieve leak-free tightness when the ball is closed and the ball opening is cross-wise to the valve body and outlet connection, it is necessary for the contact between the ball seal washer and the ball to be narrow and leak-tight and also necessary for the ball seal washers to be held against the ball surface with substantial force to prevent leakage.
In response to such high force and the resulting friction, a substantial increased amount of torque is required to turn the valve stem. In addition to the basic torque needed for an empty and idle ball valve, additional torque is needed to turn a closed ball valve having high pressure difference of 200 psi from inlet to outlet, for example. In summary, the operation torque of most ball valves is relatively high because of the force of inlet ball seal washer on ball plus the force of the outlet ball seal washer on ball, plus stem packing friction, plus side thrust friction on stem bearing surface.
Most ball valves seal around the ball by squeezing the apertured ball between two washer-like round plastic seating surfaces. When the ball aperture lines up the center axis of the ball seal washer seats, flow can occur from the ball valve body inlet through the inlet washer-seat hole, through the ball aperture hole, through the outlet washer seat hole and through the valve body outlet. When the ball aperture is rotated approximately 90 degrees by the valve stem, the ball aperture is no longer in alignment with the washer seal hole so any valve flow leakage can only occur along the solid ball surface. Since this surface is sealed against the ball seal washer seat semi-spherical surface, flow cannot occur past either the inlet washer seal or the outlet washer seal, therefore halting any flow through the valve body. Unfortunately, there is fluid trapped within the ball aperture area within the valve body that is subject to temperature change, causing volume and pressure changes, which in the case of trapped liquid, can damage the ball seal washer seats and even valve body and stem packing because of the very large bulk modulus expansion factor characteristic of a warming liquid. To avoid this, conventionally a small one millimeter or so hole is drilled through the ball center to the ball exterior at right angle to ball hole aperture and toward the upstream inlet valve opening. This overcomes bulk expansion problems but creates a valve which is not leak tight and vents the liquid to the inlet pipe of the valve, which may be very detrimental to operators or to the system. Other methods such as a tiny spring loaded relief valve are sometimes built into the valve to permit bulk modulus expansion relief, with the same disadvantages.
The common two-way shut-off ball valve uses a valve body surrounding the ball and has a pipe connection or flange connection at the valve inlet and outlet. For closed refrigeration systems, the ball valves are used to control flow of high pressure liquid from the condenser, hot gas to the condenser, hot gas from the compressor, cold gas from the evaporator to the compressor, cold pressure liquid from the accumulator to the evaporator, cold static liquid or gas between an accumulator and an evaporator, cold secondary refrigerants liquid, warm condenser liquids, and various lubricating oil circuits. In the case of cryogenic systems, the ball valve and control flow of cold liquid or gases in various circuits at flow temperatures of about −100° F. or less. For many applications, the ball valve requires insulation thickness greater than 2″ to prevent heat loss and exterior frosting or moisture condensation on the exterior surfaces of the valve body and its stem and stem housing or bonnet. Present ball valve bonnets and stems would be totally buried by such thick insulation. Alternatively, the valve stem may extend a greater distance away from the valve body (e.g. at least 18-24″) in an attempt to overcome the frosting problem. However, conventional attempts drastically increase the costs to produce and without overcoming other disadvantages described above.
Therefore, there is a need in the art for ball valves that are operable at low turning torque; that are easily converted from manual to motorized or vice versa; that do not trap liquid within the ball and cavity or safely accommodate any trapped liquid; that do not chill the exterior of the valve stem or stem housing to an extent that these valve portions would create exterior frosting or moisture condensing temperatures; that provide leak tight seating of the ball with a unique ball seal washer seat and that can be welded into piping without the need for body chilling to prevent plastic seat high temperature damage; and that provide a handle which can be locked into position and statically sealed to further prevent stem packing leakage.